Cancer is a disease which is difficult to cure and which may be fatal. Accordingly, efforts to develop new therapies for cancer are constantly ongoing in the research society. The vast majorities of cancers are present as solid tumors, e.g. lung cancer, breast cancer, prostate cancer, while the rest are hematological and lymphoid malignancies, e.g. leukemias and lymphomas.
Chemotherapy is often used in attempts to cure or palliate the disease. As cancer cells typically divide rapidly, chemotherapy usually acts by killing rapidly dividing cells. In the broad sense, most chemotherapeutic drugs work by impairing mitosis (i.e. cell division), effectively targeting fast-dividing cells. As these drugs cause damage to cells they are termed cytotoxic. Some drugs cause cells to undergo apoptosis (so-called “programmed cell death”). Often combination chemotherapy is used, when two or more drugs having different modes of action are used together in order to optimise the antitumoral effect, to minimise side effects, and prevent resistance development. The results obtained with chemotherapy vary according to tumor type. Some tumors are very sensitive and the treatment has then a high probability of leading to cure.
Chemotherapeutic drugs can generally be divided into alkylating agents, antimetabolites, anthracyclines, plant alkaloids, topoisomerase inhibitors, and other antitumor agents. The drugs affect cell division or DNA synthesis.
Alkylating agents, such as drugs derived from nitrogen mustard, that is bis(2-chloroethyl)amine derivatives, are used as chemotherapeutic drugs in the treatment of a wide variety of neoplastic diseases. Alkylating agents have the ability to covalently attach alkyl groups to electronegative sites in cells. Thus, these agents act by impairing cell function by forming covalent bonds with heteroatoms in biologically important molecules like RNA, DNA and proteins. Examples of alkylating agents are mechlorethamine, cyclophosphamide, chlorambucil, ifosfamide, temozolomide and melphalan that chemically modify a cell's DNA.
WO01/96367 discloses alkylating di- and tripeptides and one or two additional amino acids or amino acid derivatives. These derivatives were demonstrated to have an improved efficacy on a variety of tumor types.
Melphalan, i.e. p-[bis-(2-chloroethyl)amino]phenylalanine, is a conjugate of nitrogen mustard and the amino acid phenylalanine, which was synthesised in the mid 1950s (U.S. Pat. No. 3,032,584). This classic alkylating substance soon became a valuable drug in the chemotherapeutic field and is still of importance in the treatment of for example myeloma. Clinical use of melphalan in the treatment of late stage solid tumors has, however, had limited efficacy. In the search for a more selective action on malignant cells melphalan analogues have therefore been synthesised.    Larionov L. F., Cancer Res (1961), 21, 99-104 discloses various melphalan-related derivatives.    STN registry files RN: 1060633-95-5, RN: 88 7609-28-1, RN 790650-89-4, RN: 781606-39-1, RN: 773046-98-3, RN: 767621-58-9, RN: 760165-58-0 and RN: 757941-61-0 discloses various melphalan-related derivatives.    Koltun, Metal., Biopharmaceutics & Drug disposition (210), 31, 450-454 discloses forms of melphalan.    Ma D Q et al., International Journal of Pharmaceutics (1999), 189, 227-234 discloses discloses forms of melphalan.    Murav'ev I et al., Farmatsiya (1978), 27, (2), 13-15 (with abstract in Chemical Abstracts no. 1978:412066) discloses melphalan-related derivatives.
Lyophilization or freeze-drying is a method for dehydrating samples used to preserve or increase stability or to stop degradation. Due to the low water content of lyophilized products, typically around 1-4%, the action of microorganisms and enzymes is inhibited and the product life thereby increased. In lyophilization, the sample to be lyophilized is dissolved in an aqueous solution and subsequently frozen after which the surrounding pressure is reduced. The sample is then submitted to sublimation, optionally by the application of heat, in order to sublime the frozen water directly from the solid phase to the gas phase. The final water content in the product is very low, typically around 1% to 4%. Lyophilization is commonly used in the pharmaceutical field in order to increase the shelf life of pharmaceutical products.